sir c.r.reddy college of engineering eluru-534007 · 2. while performing the experiment on the...

SIR C.R.REDDY COLLEGE OF ENGINEERING ELURU-534007

FLUID MECHANICS & MACHINERY LABORATORY MANUAL

III/IV B.TECH (Mechanical): II SEMESTER

DEPARTMENT OF MECHANICAL ENGINEERING

SIR C.R.REDDY COLLEGE OF ENGINEERING, ELURU

DEPARTMENT OF MECHANICAL ENGINEERING 1

DEPARTMENT OF MECHANICAL ENGINEERING

FLUID MECHANICS & MACHINERY LAB

LIST OF EXPERIMENTS

Sl.No. Name of the Experiment Page No. 1 To calculate the co-efficient of discharge of venturimeter and to find its

variation with throat diameter. 2

2 To calculate the co-efficient of discharge and find its variation with the orifice diameters

5

3 To observe the variation in the coefficient of discharge of a mouth piece with that in the head above the mouth piece using a mouth piece apparatus by falling head method.

8

4 To observe the variation in the coefficient of discharge of a mouth piece with that in the head above the mouth piece using a mouth piece apparatus by constant head method.

10

5 To observe the variation in co-efficient of discharge of a V-notch with that in the heights of V-notch using V-notch apparatus.

12

6 To draw the characteristic curves of a reciprocating pump 14

7 To draw the performance curves of centrifugal pump 17

8 To draw the performance characteristic curves of Francis turbine 20

9 To draw the performance characteristic curves of Pelton wheel turbine 23

10 Determine co-efficient of lift and drag for given aerofoil. 26

11 To verify Bernouli’s theorem. 28

12 To determine the coefficient of friction of a pipe. 31

13 To determine Rankine’s Efficiency and D’ Aubuisson’s Efficiency of Hydraulic Ram.

33



1.VENTURIMETER

AIM: To calculate the co-efficient of discharge of Venturimeter and to find its variation with throat diameter. APPARATUS: 1) Venturimeter Test Rig 2) Stopwatch 3) Scale DESCRIPTION: The apparatus consists of 3 Venturimeters of different throat diameters provided with valves so that we can operate with one Venturimeter at one time and with the help of these, we can adjust the flow rate also. The apparatus is provided with a water tank and a collecting tank. Water in the main tank can be driven by means of a motor through the selected Venturimeter and collected in the collecting tank. Which is provided with same means to read the depth of water collected. Venturimeter is connected to a U-tube manometer by means of things, so that we can read the pressure difference. THEORY: A Venturimeter is a device used for measuring the rate of a flow of a fluid flowing through a pipe. It consists of three parts

1) A short converging part 2) Throat 3) Diverging part. It is based on the principle of Bernoulli’s equation. The discharge through Venturimeter under ideal condition i.e. theoretical flow rate is given by a1 a2 √2ghw Qth = -------------------- √a1

2 – a22

Where a1 = Cross sectional area of the inlet

a2 = Cross sectional area at the throat g = Acceleration due to gravity hw = Net pressure head of water

But actual discharge will be less than theoretical discharge & is given by Qact = Cd x Qth

Where Cd is coefficient of discharge of Venturimeter and its value is always less than 1. So Cd can be calculated as for the following formula

Qact

Cd = ---------- Qt



PROCEDURE:

1. The main tank is filled in with water and the motor connected to Venturimeter tubes is switched on.

2. First the valve of Venturimeter corresponding to throat diameter 20mm is slightly opened so that flow through the Venturimeter takes place.

3. The pressure difference in the U-tube manometer is noted down. 4. Time for 5 cm rise of water level is noted down.

5. The valve is further opened in order to attain different flow rates and the above procedure is repeated for three times and totally four readings are tabulated.

6. The above procedure is repeated for the remaining two Venturimeters of throat diameters 25 mm and 40 mm respectively.

PRECAUTIONS:

1. While adjusting the mercury limbs in U-tube manometer care should be taken to avoid any expelling out of mercury.

2. While performing the experiment on the Venturimeter the two remaining valves corresponding to two Venturimeters should be closed.

3. Time taken for 5 cm rise in water level in the collecting tank should be noted carefully.

S.No

Time taken for 5 cm rise of water level

Manometer readings

h1-h2 hm = ---------- 100 meters

Qth

Qact

Cd

h1 cm

h2 cm

MODEL CALCULATIONS: a1 a2 √2ghw Qth = ------------------- √a1

2 – a22

a2 / a1 = 0.35

Where a1 = Cross sectional area of the inlet = π /4 x d1

2 a2 = Cross sectional area at the throat d1 = Dia of the inlet pipe g = Acceleration due to gravity



hw = Net pressure head of water in meters

⎟⎟⎠

⎞⎜⎜⎝

⎛−

ρ

ρ− 1hh

w

mmw

hm = Net pressure head of mercury manometer in meters ρm = Density of mercury = 13,600 kg / m3 ρw = Density of water = 1000 kg / m3

Qact = A x H / t

Where A = Area of the collecting tank = 0.1979 m2 H = Rise of water in collecting tank with in the time ‘t’ in meters t = time taken for 10 cm rise of water in collecting tank (in seconds)

Qact Cd = ----------

Qth

Where C d = Coefficient of discharge of Venturimeter GRAPHS: wsact HVQ)1 thactVsQQ)2 Take Qact on Y-axis RESULT: Mean value of Cd of Venturimeter =

Cd of Venturimeter by Graph =



2.ORIFICEMETER

AIM: To calculate the co-efficient of discharge and find its variation with the orifice diameters APPARATUS: 1) Orificemeter Test Rig 2) Stop Watch 3) Scale DESCRIPTION: The apparatus consists of 3 orifice meters of different orifice diameters provided with valves so that we can operate with one Orificemeter at one time and with the help of these we can adjust the flow rate also. The apparatus is provided with a tank of water and a collecting tank. Water in the main tank can be driven by means of a motor through the selected Orificemeter and collected in the collecting tank which is provided with same means to read the depth of water collected. Orificemeter is connected to a tube manometer by means of tubings, so that we can read the pressure difference. THEORY: Orifice meter is a device used for measuring the rate of flow of a fluid through a pipe. It also works on the same principle as that of Venturimeter. It consists of a flat circular plate which has a circular sharp edged hole called orifice, which is concentric with the pipe. The co-efficient of discharge for orifice meter is much smaller than that for a Venturimeter.

The discharge through Orificemeter under ideal condition i.e. theoretical flow rate is given by a1 ao √2ghw

Qth = -------------------- √a1

2 – ao2

Where a1 = Cross sectional area of the pipe ao = Cross sectional area of the orifice g = Acceleration due to gravity hw = Net pressure head of water

But actual discharge will be less than theoretical discharge & is given by Qact = Cd x Qth

Where Cd is coefficient of discharge of Orificemeter and its value is always less than 1. So Cd can be calculated as for the following formula

Qact Cd = ----------

Qth PROCEDURE:

1. The main tank is filled in with water and the motor connected to Orificemeter tubes is switched on

2. First the valve of Orificemeter corresponding to throat diameter 20 mm is slightly opened so that flow through the Orificemeter tubes takes place.

3. The pressure difference in the U-tube manometer is noted down 4. Time for 5 cm rise of water in the U-tube manometer is noted down

5. The value is further opened in order to attain different flow rates and the above procedure is repeated for three times and totally your readings tabulated



6. The above procedure is repeated for the remaining two Orificemeters of throat diameters 25 mm and 40 mm respectively.

PRECAUTIONS: 1. While adjusting the mercury limbs in U-tube manometer care should be taken to avoid

any expelling of mercury out. 2. While performing the experiment on the Orificemeter, the two measuring valves

(remaining valves) corresponding to two Orificemeters should be closed. 3. Time taken for 5 cm rise in water level in the collecting tank should be noted carefully

OBSERVATIONS: S.No

Time taken for 5 cm rise of water level

Manometer readings

h1-h2 hm = ---------- 100

meters

Qth

Qact

Cd

h1 cm

h2 cm

MODEL CALCULATIONS: a1 ao √2ghw

Qth = -------------------- √a1

2 – ao2

a0 / a1 = 0.45

Where a1 = Cross sectional area of the pipe = π /4 x d12

ao = Cross sectional area of the orifice d1 = Dia of the pipe g = Acceleration due to gravity hw = Net pressure head of water

⎟⎟⎠

⎞⎜⎜⎝

⎛−

ρ

ρ×= 1hh

w

mmw

hm = Net pressure head of mercury mano meter ρm = Density of mercury = 13,600 kg / m3 ρw = Density of water = 1000 kg / m3

Qact = A x H / t



Where A = Area of the collecting tank = 0.1979 m2 H = Rise of water in collecting tank with in the time ‘t’ in meters t = time taken for 10 cm rise of water in collecting tank (in seconds)

Qact Cd = ----------

Qth

Where C d = Coefficient of discharge of Orificemeter GRAPHS: wact H Vs Q 1) thact Q VsQ 2) Take Qact on Y-axis RESULT: Mean value of Cd of Orificemeter = Cd of Orificemeter by Graph =



3.MOUTH PIECE (FALLING HEAD METHOD) AIM: To observe the variation in the coefficient of discharge of a mouth piece with that in the head above the mouth piece using a mouth piece apparatus by falling head method. APPARATUS: 1) Mouth piece apparatus, 2) Stop watch, 3) Scale DESCRIPTION: The apparatus consists of a mouthpiece fitted to one side of a vertical tank, main water tank and a collecting tank. Water in the main tank can be driven by means of a motor so that it flows in the mouthpiece fitted tank and there by into the collecting tank through the mouth piece. A valve is provided at the site of motor so that flow in the mouth piece fitted tank can be adjusted. The vertical tank is provided with some scale to measure the head of water above the mouth piece. The collecting tank is provided with some scale to read the water level in it and there by volume of water collected can be computed. THEORY: Mouth piece is a short length pipe which is two or three times its diameter in length, fitted in a tank or vessel containing fluid. It is used to measure the rate of flow of fluid. Mouth piece fitted external to the tank is called external mouthpiece (this is the present use with our experiment). The jet of liquid entering the mouth piece constructs to form a vena – contracta. Beyond this section jet again expands and fill the mouth piece completely. Measurement of coefficient of discharge by falling head method 2A(√H1 – √H2)

Coefficient of discharge = Cd = ------------------------------ (a x t x √2g)

Where A = area of the over head tank H = head of water above the mouth piece

a = area of mouth piece t = time for water level to fall by 5 cm

PROCEDURE: 1) The mouthpiece fitted tank is completely filled with water. 2) Starting from say40 cm above the mouthpiece (i.e head) time taken for water level to drop

by say 5cm is noted. 3) Now time for water level to drop from 35 to 40cm is noted

4) Similarly 5 to 6 readings are noted. 5) The readings are tabulated.



PRECAUTIONS: 1) Head above the mouthpiece should be noted carefully.

2) Time for rise in water level in collecting tank and that for fall in water level in mouth piece fitted tank should be correctly noted.

OBSERVATIONS:

S.No Water head above the mouth piece Time taken for 5 cm fall of water level

Cd Initial H1 Final H2

MODEL CALCULATIONS: 2A(√H1 – √H2)

Coefficient of discharge = Cd = ------------------------------ (a x t x √2g)

Where A = area of the over head tank = 0.34 X 0.35 = 0.119 m2 H1 = Initial head of water above the mouth piece = H2 = Final head of water above the mouth piece =

a = area of mouth piece (π/4 d2) d = Diameter of the mouth piece = 0.01 m

t = time for water level to fall by 5 cm GRAPHS: t Vs 21 HH − RESULT: Mean value of Cd of mouth piece =



4.MOUTH PIECE (CONSTANT HEAD METHOD)

AIM: To observe the variation in the coefficient of discharge of a mouth piece with that in the head above the mouth piece using a mouth piece apparatus by constant head method. APPARATUS: 1) Mouth piece apparatus, 2) Stop watch, 3) Scale DESCRIPTION: The apparatus consists of a mouthpiece fitted to one side of a vertical tank, main water tank and a collecting tank. Water in the main tank can be driven by means of a motor so that it flows in the mouthpiece fitted tank and there by into the collecting tank through the mouth piece. A valve is provided at the site of motor so that flow in the mouth piece fitted tank can be adjusted. The vertical tank is provided with some scale to measure the head of water above the mouth piece. The collecting tank is provided with some scale to read the water level in it and there by volume of water collected can be computed. THEORY: Mouth piece is a short length pipe which is two or three times its diameter in length, fitted in a tank or vessel containing fluid. It is used to measure the rate of flow of fluid. Mouth piece fitted external to the tank is called external mouthpiece (this is the present use with our experiment). The jet of liquid entering the mouth piece constructs to form a vena – contracta. Beyond this section jet again expands and fill the mouth piece completely. Measurement of coefficient of discharge by Constant head method

Theoretical discharge = Qth = a √2gH Where a – area of mouth piece H – head of water above the mouth piece Actual discharge = Qact = (A X h) / t Where A – area of the collecting tank h – rise in water level And t – time for water level to rise by h

Coefficient of discharge is defined as the ratio of actual discharge to theoretical discharge

Cd = Qact / Qth PROCEDURE: 6) The main tank is filled with water and the motor is switched on

7) Valve at the motor site is closed to transfer in to the vertical mouth piece fitted tank 8) Time is allowed for the water level to settle at some height above the mouth piece

9) The head of water above the mouthpiece is measured by means of the scale provided at the side of the tank.



10) Time for 5am rise in water level in the collecting tank is noted. 11) The valve at motor site is further closed to achieve another flow rate and the above

procedure is adopted. 12) In this manner for 2 more times the similar procedure is repeated and the readings are

noted. 13) Readings at 4 different heads are noted in a tabular form..

PRECAUTIONS: 1) Head above the mouth piece should be noted carefully.

2) Time for rise in water level in collecting tank and that for fall in water level in mouth piece fitted tank should be correctly noted.

OBSERVATIONS: S.No Time taken

for 5 cm rise of water level

Head above mouth piece

H cm

Qact

Qth

Cd

MODEL CALCULATIONS:

Theoritical discharge = Qth = a √2gH Where a – area of mouth piece = πd2/4 d = dia of mouth piece = 0.01 m H – head of water above the mouth piece in meters Actual discharge = Qact = (A X h) / t Where A – area of the collecting tank = .45x 0.55 = 0.2475 m2 h – rise in water level (in meters)

t – time for water level to rise by h

Cd = Qact / Qth

GRAPHS: H Vs Q 1) act thact Q VsQ 2) Take Qact on Y-axis RESULT: Mean value of Cd of mouth piece = Cd of mouth piece by Graph =



5.V– NOTCH AIM: To observe the variation in co-efficient of discharge of a V-notch with that in the heights of V-notch using V-notch apparatus. APPARATUS: 1) V-Notch Test rig, 2) Stop Watch, 3) Scale DESCRIPTION: The apparatus consists of a V-notch fitted to inside of a channel in rectangular shape, another side of which is closed, main water tank and a collecting tank. Water in the main tank can be driven by means of a motor so that water flows in to the channel and there by in to the collecting tank through V-notch. A valve is provided at the motor site so that the flow rate through V-notch can be adjusted. The channel is provided with some means to read the V-notch height. The collecting tank is also provided with some means to read the rise in water level and there by volume of water collected can be measured. THEORY: A notch is a device used for measuring the rate of flow through a small channel or a tank. It may be defined as an opening in the side of a tank or a small channel in such a way as liquid surface in the tank or channel is below the top edge of the opening.

Theoritical discharge through V-notch is given by Qth = 8/15 tan θ/2 √2g H5/2 Where θ = V-notch angle H = head of water above the notch Actual discharge through V-notch is given by

Qact = thA×

Where A = area of the collecting tank h = rise in water level in the collecting tank And t = time for water level to rise by h Co-efficient of discharge through V-notch is defined as the ratio of actual discharge to the theoritical discharge Cd = Qact / Qth PROCEDURE: 1. The main tank is filled with water and the motor is switched on

2. Value at the motor site is closed to transfer water rate in to the rectangular channel 3. The valve is opened completely to cease the water flow into the channel when the water

level exceeds the notch bottom 4. Time is allowed for the water to flow through the notch till the level settles at the bottom

level of notch



5. Scale provided at the rectangular tank (channel) is adjusted at zero for the present water level

6. Now the valve at the motor site is closed tightly so that water moves into the tank and some time is allowed for the water level to settle at constant height

7. The head of water above the notch is read by means of the scale provided 8. By means of a stop watch, time for 5 cm rise in water level in the collecting tank is

measured 9. The valve at motor site is further closed so that water rises in the rectangular tank and the

above described procedure is repeated and the readings are tabulated PRECAUTIONS: 1. Initially water in the rectangular channel (tank) should be in plane with that of V-notch

bottom 2. Head above the V-notch should carefully be noted 3. Time taken for 5 cm rise in water level should be read accurately OBSERVATIONS: S.No Time taken

for 5 cm rise of water level

Head above notch H cm

Qact

Qth

Cd

MODEL CALCULATIONS: Qth = 8/15 tan θ/2 √2g H5/2

Where θ = V-notch angle = 60o H = head of water above the notch

Qact = (A X h)/t

Where A = area of the collecting tank = 0.54 x 0.44 = 0.2376 m2 h = rise in water level in the collecting tank (in meters) And t = time for water level to rise by h

Cd = Qact / Qth

GRAPHS: 5/2act H Vs Q 1) thact Q VsQ 2) Take Qact on Y-axis

RESULT: Mean value of Cd of V- notch = Cd of V- notch by Graph =



6.RECIPROCATING PUMP AIM: To draw the characteristic curves of a reciprocating pump APPARATUS: Reciprocating pump test rig, tachometer and stopwatch DESCRIPTION: The experiment setup is a closed circuit type, it mainly consists of 1. Double acting reciprocating pump 2. A single speed 1 HP AC motor with rated speed of 1420 rpm. 3. A piping system and measuring tank . 4. A stepped pulley arrangement for changing of speed. 5. In put power measuring arrangement. 6. Sump.

The reciprocating pump is a double acting type. The suction and delivery pipes are 1” and ¾” in diameter. The pump is driven by a V-belt from the motor through the pulley arrangement, the measuring tank size is 0.3m x 0.3 m THEORY: A reciprocating pump essentially consists of a piston or plunger which moves to and fro in a closed fitting cylinder. A typical double acting cylinder is connected to suction and delivery pipes, each of which is provided with a non return valve. The piston is connected to a crank by means of connecting rod. During the suction stroke, the crank rotates from 0 to 180 degrees and a partial vaccum is created in the cylinder, which enables the atmospheric pressure acting on the liquid surface in the sump below, force the liquid up the suction and fill the cylinder by opening the suction valve. During the delivery stroke the crank rotates 1800 to 3600 and the piston forces the water to go out of the cylinder through the delivery valve. The operating characteristic curves of a reciprocating pump are obtained by plotting the discharge Q power input P and overall efficiency η against the head developed by the pump H when it is operating at constant speed.



PROCEDURE : 1) The pump is filled with sufficient amount of water and the pump is primed if necessary.

2) The delivery valve is kept open and the pump is started and is run at a particular speed. The speed of the pump is measured with the help of a tachometer.

3) The actual discharge Q is measured by noting the time taken for a rise in height of water in the measuring tank.

4) The input power is calculated by noting the time taken for 5 revolutions of the energy meter disc.

5) Suction and delivery pressures are noted from the pressure gauges. 6) Position of delivery valve is slightly altered for different delivery pressures and another

set of readings of suction pressure, delivery pressure and discharge are found. 7) Characteristic curves are plotted according to the values obtained.

PRECAUTIONS:

1. The delivery valve should be completely closed before starting and stopping of the pump 2. Priming is done for the pump before starting

OBSERVATIONS: S.No

Speed (N) rpm

Time taken for 5 rev disc t

Time taken for 5cm rise of water T

Suction head Ps

Delivery Head Pd

H meters

Input power W

Out put power W

η = (Op/Ip) x 100

Discharge Q(m3/sec)

MODEL CALCULATIONS:

1. Input power = CEt

n.10003600

×

××

n = no. of rev of the energy meter disc = 5 rev t = time taken for 5 rev of the disc E.C = Energy meter constant = 1200 rev/kwh



2. Output power = WQH W = Specific weight of water = 9810 N/m3

Q = ThA×

Q = Discharge of the pump A = area of the collecting tank = 0.3 x 0.3

h = height of the water level in the tank T = time taken for 5 cm rise of water level

H = 10.331.033P

760P ds ×⎥

⎦

⎤⎢⎣

⎡+ m of water head

Ps = Vacuum pressure in mm of Hg

Pd = Delivery pressure in Kg/cm2

3. Efficiency of pump η = 100×inputpower

routputpowe

GRAPHS:

1) Head Vs Discharge 2) Head Vs Efficiency 3) Head Vs Power

RESULT: The performance curves of the pump are obtained.



7.CENTRIFUGAL PUMP AIM: To draw the performance curves of centrifugal pump APPARATUS: Centrifugal test rig, Stop watch, Tachometer THEORY: The hydraulic machine converts the mechanical energy into the pressure energy

or hydraulic energy. The machine, which converts the mechanical energy to the hydraulic

energy by means of centrifugal force, that hydraulic machine is known as centrifugal pump.

The centrifugal pump works on the principle of force vortex flow by means

that when certain mass of fluid is rotated by means of any external force. There will

be rise of pressure of the fluid at its centre of rotation takes place at the outlet of the

impeller when the radius is more, the rise in head is more and the discharge is also

high. Due to this rise in pressure head this pressure head can be used to rise the fluid

to a high level.

PROCEDURE: 1. The sump is filled with sufficient amount of water keeping the delivery valve fully

closed, the pump is started 2. Priming is done for the pump before starting



3. Then the valve is slowly opened and the actual discharge is found by noting the time taken for 5 cm raise of water level.

4. The time taken for 5 revolutions of the energy meter disc is noted and by using this time

the input power can be known 5. The suction and delivery pressure are known by the pressure gauges 6. The procedure is repeated for different set of readings PRECAUTIONS: 3. The delivery valve should be completely closed before starting and stopping of the pump 4. Priming is done for the pump before starting OBSERVATIONS: S.No

Speed

(N)

rpm

Time taken for 5 rev disc

t

Time taken

for 5cm rise of water

T

Suction

head

Ps

Delivery

Head

Pd

H

meters

Input powe

r

W

Out put power

W

η = (Op/Ip) x 100

Discharge

Q(m3/sec)

MODEL CALCULATIONS:

4. Input power = CEt

n.10003600

×

××

n = no. of rev of the energy meter disc = 5 rev t = time taken for 5 rev of the disc E.C = Energy meter constant = 150 rev/kWh

5. Output power = WQH

W = Specific weight of water = 9810 N/m3

Q = ThA×

Q = Discharge of the pump in m3/sec A = area of the collecting tank = 1x 0.4 m2

h = height of the water level in the tank in m

T = time taken for 5 cm rise of water level

H = 10.331.033P

760P ds ×⎥

⎦

⎤⎢⎣

⎡+ m of water head



Ps = Vacuum pressure in mm of Hg

Pd = Delivery pressure in Kg/cm2

6. Efficiency of pump η = 100×inputpower

routputpowe

GRAPHS:

4) Discharge Vs Head 5) Discharge Vs Efficiency

6) Discharge Vs Power

RESULT: The performance curves of the pump are obtained.



8.FRANCIS TURBINE AIM: To draw the performance characteristic curves of Francis turbine APPARATUS: Closed circuit experiment setup containing Francis turbine, tachometer, weights THEORY: Radial flow turbines are those turbines in which the water flows in the radial direction. The water may flow radially from outwards to inwards or vice versa. If the water flows from outwards to inwards through the runner, the turbine is known as inward flow reaction turbine. Reaction turbine means that the water at the inlet of the turbine possess kinetic energy as well as pressure energy. As the water flows through the runner, a part of pressure energy goes on changing into kinetic energy The inward flow reaction turbine having radial discharge at outlet is known as Francis turbine. In the modern Francis turbine, the water enters the turbine in the radial direction at the outlet and leaves in the axial direction at the inlet of the runner. The main parts of the turbine are

1. Casing 2. Runner 3. Guide mechanism 4. Draft tube



PROCEDURE: 1. The pump is filled with sufficient amount of water and the pump is primed if necessary

2. The turbine is kept in the unloaded position. The gate valve and the manometer cocks are kept closed

3. The pump is started and the gate valve is slowly opened. The amount of water entering the casing is adjusted by turning the wheel connected to the guide valves

4. The speed of the turbine is measured and the manometer readings are noted. The head of the turbine is measured.

5. The turbine is gradually loaded from lower to higher weights and the speed, manometer readings, load applied are noted for each step of loading

6. The above procedure is repeated for ½, 3/4th, fully open conditions of the gate valve PRECAUTIONS:

1. Before the experiment is started, it must be checked that the gate valve and the cocks of the manometer are closed.

2. The water used must be free from dust 3. The cocks of the manometer must be opened gently

OBSERVATIONS: Gate opening

Speed N (rpm)

Pressure gauge reading P1 Kg/cm2

Head of the Water

H meters

Manometer readings Load applied W(kg)

Spring balance reading S(kg)

Net load (kg) W - S

WP BP

η Nu

Pu Qu

h1 Cm

h2 cm

h=(h1-h2)x 10 mm

¼ ½ ¾ full

MODEL CALCULATIONS:

Input Power =Water power = 1000WQH in Kw

W = 9810 N/m3

Q = ⎟⎟⎠

⎞⎜⎜⎝

⎛ ×

60000h5.84 in m3/sec

84.5 = Venturimeter constant h = Manometer reading in mm of Hg

H = ( )33.101.0331.033P1 ×⎟

⎠

⎞⎜⎝

⎛ + in meters of water



1P = Pressure gauge reading in Kg/cm2

Brake power = Output Power =600002 NTπ Kw

N = Speed of brake drum dynamometer in rpm T = ( ) 162.081.9 ××− SW N-m

Efficiency η = 100×inputoutput

Unit speed Nu = HN

Unit discharge Qu = HQ

Unit power Pu = 23H

P

P = Brake Power GRAPHS: 1. Unit Speed Vs Unit Discharge 2. Unit Speed Vs Unit Power 3. Unit Speed Vs Efficiency

RESULT: The performance characteristic curves of Francis Turbine are obtained.



9.PELTON WHEEL AIM: To draw the performance characteristic curves of Pelton wheel APPARATUS: Closed circuit experimental setup containing Pelton wheel, tachometer, Weights THEORY: The Pelton wheel or Pelton turbine is a tangential flow impulse turbine. The water strikes the bucket along the tangent of runner. The energy available at the runner is only kinetic energy. The pressure at the inlet and outlet of the turbine is atmospheric. This turbine is used for high heads The water flows from the reservoir and flows through the penstock at the outlet of which a nozzle is fitted, the nozzle increases the kinetic energy of water flowing through the penstock. At the outlet of the nozzle, the water comes out in the form of a jet and strikes the buckets of the runner. The main parts of the Pelton wheel are 1. Nozzle and flow regulating arrangement 2. Runner and buckets 3. Casing and braking jet

PROCEDURE: 1. The pump is fitted with sufficient amount of water and the pump is primed if necessary

2. The turbine is kept in the unloaded position, gate valve and cocks of the manometer are kept constant

3. The pump is started and the gate valve is slowly opened. The amount of water striking the wheel is adjusted by keeping the spear in 1/4th open conditions

4. The speed of the turbine is measured and the manometer reading is noted. The head on the turbine is measured



5. The turbine is gradually loaded from lower to higher weights and the speed, manometer reading and the load applied are noted in each case

6. The above procedure is repeated for ½, ¾ th, fully open conditions. PRECAUTIONS:

1. The gate valve and cocks of the manometer must be closed at the initial stage 2. Water used must be free from dust

3. Manometer readings are taken with out parallax error 4. Cocks of the manometer must be opened gently

OBSERVATIONS: Gate opening

Speed N (rpm)

Pressure gauge reading P1 Kg/cm2

Head of the Water

H meters

Manometer readings Load applied W(kg)

Spring balance reading S(kg)

Net load (kg) W - S

WP BP

η

Nu

Pu

Qu h1

Cm

h2 cm

h=(h1-h2)x 10 mm

¼ ½ ¾ full

MODEL CALCULATIONS:

Input Power =Water power = 1000WQH in Kw

W = 9810 N/m3

Q = ⎟⎟⎠

⎞⎜⎜⎝

⎛ ×

60000h7.35 in m3/sec

35.7 = Venturimeter constant

h = Manometer reading in mm of Hg

H = ( )33.101.0331.033P1 ×⎟

⎠

⎞⎜⎝

⎛ + in meters of water

1P = Pressure gauge reading in Kg/cm2

Brake power = Output Power =60000NT2π Kw

N = Speed of brake drum dynamometer in rpm T = ( ) 162.081.9 ××− SW N-m



Efficiency η = 100×inputoutput

Unit speed Nu = HN

Unit discharge Qu = HQ

Unit power Pu = 23H

P

P = Brake Power GRAPHS: 4. Unit Speed Vs Unit Discharge 5. Unit Speed Vs Unit Power 6. Unit Speed Vs Efficiency RESULT: The performance characteristic curves of Pelton Wheel are obtained.



10.LIFT AND DRAG COEFFICIENT FOR AN AEROFOIL Aim:

To determine the lift and drag forces for the given aerofoil and hence to obtain co-efficient of lift and coefficient of drag. Apparatus: 1. Wind tunnel test rig

2. NACA 0018 aerofoil of axial chord = 16 cm and Span = 25 cm 3. NACA 0018 aerofoil with a linkage mechanism and a digital component force measuring

transducer to determine lift and drag forces. 4. A pitot - static tube with a U-tube water manometer

Description:

The wind tunnel is of suction type with an axial flow fan driven by a variable speed DC motor. It consists of an entrance section with a bell mouth inlet containing a flow straighter, screen and a straw honey combs. This section is followed by a nozzle section, test section, a diffuser section and a duct containing the axial flow fan. The whole unit is supported on steel frame. The complete wind tunnel except the test section is constructed of MS sheets for strength and rigidity. The test section is made of teak wood and has plexiglass window for visual observations of flow phenomena. The control of the DC motor is by a rectifier controlled variable speed drive. Theory:

Wind tunnel is generally used for testing the models of various shapes like aerofoils, cylinders, cascade of blades etc. In a wind tunnel the important part is the test section. The aim is to obtain a truly rectilinear flow across the test section. The object to be tested are placed in the test section. The wind tunnel can be of suction type or blower type. The air enters in to the settling chamber on account of the large cross section area of the setting chamber. Its velocity is reduced, and the presence of wire gauges and honey comb straightens the flow before it is expanded in the contraction zone. The working or test section receives a uniform stream of air from the contraction zone. Procedure:

1. The given aerofoil is rigidly fixed in the test section to the vertical rod extending from the transducer. The angle of incidence (α) is kept at zero initially.

2. The transducers are connected to the digital display device where the lift and drag forces can be read directly.

3. The motor is started and speed is increased gradually. So that manometer deflection from the pitot tube is at least 5 cm.

4. The lift force & drag force are noted from the display device 5. The angle of incidence is altered to different angles and the readings of lift and drag

forces are noted. 6. Graphs are plotted for CL CD Versus incidence angle.



Observations:

S.No Angle of incidence α (Deg)

Pitot tube reading q (cm)

Drag force FD

(kgf)

Lift force FL

(kgf)

Model Calculations:

Incidence angle (α) = 00

Pitot tube reading = q cm

Velocity (V) = 13 √q m/s Drag Coefficient (CD):

Drag coefficient (CD) = AV

21F2

D

×ρ

Where A = Chord x span Lift Coefficient (Cl):

Lift coefficient (CL)= AV

21F2

L

×ρ

Results:

SNo Angle of incidence α (Deg)

Velocity of Air V

(m/sec)

Drag Coefficient

(CD)

Lift Coefficient (CL)

Precautions:

1. When the power is turned with main switch, the speed control knob of the motor should be kept at minimum.

2. The DC motor should not be operated at low inlet voltages. 3. The aerofoi1 should be tight in its position while taking the readings for a particular

incidence angle.



11.VERIFICATION OF BERNOULLI’S THEOREM Aim:

To verify Bernoulli’s theorem. Theory:

The Bernoulli’s theorem states that for steady, uniform & laminar flow of an

incompressible fluid, the total energy per unit weight or total head of each particle remains

same along a stream line provided no energy is gained or lost.

Most of the hydraulic studies are based on the principle of Bernoulli’s theorem. Verification of the above principle experimentally helps in better understanding of the principles of hydraulics flow.

Mathematically, Bernoulli’ s theorem can be expressed as Total head (or) Total energy per unit weight,

=++=wp

g2vzH2

t

Where, Z = datum head = position of center of conduit with respect to datum

g2v2 = Velocity Head

Q = Actual Discharge

V = Velocity of flow = AQ = _____________

A = Cross sectional area

g = Acceleration due to gravity

wp = Piezometric head or pressure head

w = Specific weight i.e., weight per unit volume = g×ρ = 9810 N/m3

ρ = Mass density is the mass per unit volume for water

Apparatus: Bernouli’s Apparatus

Collecting tank with piezometer Stopwatch to measure the time of collection

Meter scale to measure the internal dimensions of the collecting tank

Constant



Description Of The Equipment:

The experimental set up consists of a convergent- passage of rectangular cross section made out of clear transparent sheet to facilitate visual observation of the flow. The passage walls are so made that the top of the wall is horizontal and the sidewalls are vertical and mutually parallel to each other. The lower wall is so constructed that it gives the passage to the required convergence and divergence. The total length of test section of the passage divided in to a number of equal lengths, where piezometric tubes are fitted. Each of these piezometric tubes is provided with a scale to measure the pressure energy or pressure heads.

At both the ends of the passage tanks are provided, which help to stabilize the flow. The calibrated scale is provided to measure the volume of water in the measuring tank based on the water level in the gauge glass.

The setup is provided with an arrangement for injecting a dye ( color) into the passage at its entrance a fine nozzle with the help of which usual observation of the flow can be made Procedure:

1. The experiment is conducted with datum line taken at the center line of the rectangular channel of varying cross sections and is same at all sections and considered ‘zero’ as its value.

2. Open the inlet valve to allow the flow from the supply tank through the conduct. Also admit the dye into the passage.

3. Adjust the outlet valve of the apparatus, so that a constant head is maintained in the supply tank of the apparatus.

4. Remove air bubbles in the piezometer tubes. Measure the pressure heads at various sections of the conduit with the piezometers placed at each section.

5. Note the time ‘t’ for collection of water to the known rise ‘H’ of water level in the collecting tank.

6. Calculate velocity and hence velocity head. 7. Tabulate the observations and calculate the total heads.

Specimen Calculations:

(Reading No: ) Area of the collecting tank, A = L x B = 0.3 x 0.3 = 0.09 m2

Discharge, t009.0

t1.0x09.0

tAHQ === m3 / s

Velocity, aQv = = m/s

Velocity head, g2v2 = m



Pressure head, wph = = m

Cross section Time for ‘H’ m rise ‘t’ in sec

Avg time ‘t’ in sec

Discharge

tAHQ =

in m3/s

Velocity

aQv =

in m3/s

Velocity head,

g2v2

in m/s

Pressure head,

wph =

in m

Datum head Z

in m

Total head

wp

g2vzH2

t ++=

in m

No Area 10-4 m2

1 2

1 a1=1.8

2 a2=1.6

3 a3 = 1.4

4 a4=1.2

5 a5=1

6 a6=1.1

7 a7=1.2

8 a8=1.3

9 a9=1.4

10 a10=1.5

11 a11=1.6

12 a12=1.7

13 a13=1.8

14 a14=1.9

Datum head, z = m

Therefore, total head at each station, wp

g2vzH2

t ++= = m

wp

g2vzH

wp

g2vzH 2

22

2t1

21

1t ++==++=∴ = Constant

Graph:

The graphs of pressure head, velocity head and total head are drawn at various cross-sections, taking the cross section area on X-axis.



12.CO-EFFICIENT OF FRICTION IN PIPES Aim:

To determine the Coefficient of Friction of a pipe Theory:

When a liquid flows through a pipe it looses some of its energy in over coming the frictional resistance. Hence, the pressure applied at one end of the pipe does not reach the other end, due to the friction. This loss in pressure head is called the frictional loss and it depends upon the contact area, velocity of flow and length of pipe. Determination of Co-efficient of friction helps to determine the head loss in the flow as it flows from one point to other.

Apparatus:

Ø Test pipe with valves to control now Ø Manometer or any pressure measuring device to measure the pressure difference

between points of observation Ø Collecting lank to collect the discharge through pipe

Ø Stop Watch to determine the time of collection of water to know raise of water level in the tank

Ø Scale to measure the plan dimensions of collecting tank Description of apparatus:

The test rig consists of a pipe length with inlet and outlet control valves. Two pressure tapings are made at a length (1 meter) and connected to a U-tube mercury manometer or any pressure measuring devices to measure the pressure difference between the two points of observation. A collecting tank is provided at the out let end to collect the discharge and to find out the actual discharge. Procedure:

1. Open the inlet valve and allow the liquid to flow through the pipe 2. Note the left limb and right limb readings in the manometer or pressure gauge

readings at the point of observation. 3. Close the outlet valve in the collecting tank

4. Note the time taken for ‘H’ mm raise of water level in collecting lank 5. Increase the discharge by opening the inlet valve and repeat for at least five times

Observations & Tabulations:

Manometric readings in left limb of the manometer, h1 = m Manometric readings in right limb of the manometer, h2 = m

Specific gravity of manometer liquid, (Mercury) Sm = 13.6



Specific gravity of flowing liquid, (water) Sf = 1.0 Co-efficient of friction, f =

Length of pipe between the points of observation, l = m

Velocity of flow in pipe, aQv = , v = m/sec

Cross sectional area of pipe, a = m2 Diameter of pipe, d = m

Internal plan area of collecting tank, A = m2 Rise of liquid level in the collecting tank, H = m

Time of collection for ‘H’ rise in the collecting tank, t = sec

Discharge through the pipe, tAHQ = Q = m3/sec

S.No Manometer readings Loss of head

⎥⎦

⎤⎢⎣

⎡ −=

f

fmf S

SSxh

= 12.6 x (mm)

Time taken for ‘H’ mm of rise (sec)

Discharge

tAHQ =

(m3/sec)

Velocity

aQV =

m/sec

Coefficient of friction,

2f

v.l.4d.g.2.hf =

Left Limb h1 (mm)

Right Limb h2 (mm)

Difference, x = (h1-h2) (mm)

1 2 3 4 5 6

Specimen calculation:

Actual Discharge, tAHQact = = m3/sec

Area of tank, A = m2

Rise of water, H = m Time taken for ‘H’ m rise of water, t = sec

Lose of head in terms of flowing liquid due to friction,

( )( )⎟⎠

⎞⎜⎝

⎛ −−=⎟⎟

⎠

⎞⎜⎜⎝

⎛ −=

1hh16.13

SSSxh 21

f

fmf

Coefficient of friction, 2f

v.l.4d.g.2.hf =

Graph: Draw the graph between hf Vs g2V2

with hf on y-axis

Result: The coefficient of friction for the given pipe, f =



13.HYDRAULIC RAM Aim:

To determine Rankine’s Efficiency and D’Aubuisson’s Efficiency of Hydraulic Ram Apparatus:

Closed circuit Hydraulic Ram Apparatus, Stop watch Theory:

The Hydraulic Ram is a type of pump in which the energy of large quantity of water falling through small height is utilized to lift a small quantity of this water to a greater height No external power is therefore required to operate this pump. Hydraulic Ram consists of a valve chamber having a waste valve and delivery valve. The waste valve opens into an air vessel to which a delivery pipe is connected. This valve opens into an air vessel to which a delivery pipe is connected. This delivery pipe carries water to the delivery tank. The valve chamber is connected to a low level supply tank through a supply pipe.

The working of Hydraulic Ram is based on the principle of water hammer or inertia

pressure developed in the supply pipe. When the waste valve is remains closed then the hydraulic ram does not function at all. When the waste valve kept open, then water in the pipe begins to run through waste valve and the flow is set up. The velocity of water in drive pipe increases under the supply head.

During this period the dynamic pressure of the water under side of valve will become greater than the dead weight of the waste valve at one stage, then the waste valve gets closed. Due to this the momentum of moving column of liquid in the pipe is destroyed. This change in momentum results in increased pressure in the valve chamber. If this pressure exceeds, the pressure in the topside of the delivery valve due to the column of water in the delivery pipeline and then the delivery valve opens. The cater from valve chamber rushes into air vessel and then flow through the delivery pipeline to delivery tank.

Procedure: 1) Fill the supply tank by water. 2) Select particular stroke of waste valve. Then start the priming in valve chamber by

using waste valve. After some time valve starts moving by its own and water starts collecting in waste water tank and also starts delivering through delivery pipe.

3) Then start the pump. 4) Measure the water column height in waste water tank for particular number of

strokes and time & note it down. 5) Then measure the water column height in the delivery tank for same number of

strokes and note down time. 6) Take number of readings by varying the lift of waste valve. 7) Do the calculations as per given below and find out the Ram Efficiency.



Observations:

1) Delivery Tank size : 290 x 290 mm = 0.0841 m2 2) Waste water tank size : 390 x 390 mm = 0.1521 m2 3) Supply Head (H) : l.4m 4) Delivery Head ( hd ) : 2.8m

Observation Table :

Sr No

Waste

valve lift

in mm

No of

stroke per min of

waste

valve

Waste water tank Delivery tank

D’Aubuisson’s Efficien

cy

Rankine’s

Efficiency

Height of water column ‘X’ in

glass tube

Time ‘T in sec for ‘X’ mm height

Water discharge ‘Q’

in m3/sec

Height of

water column ‘y’

in glass tube

Time ‘t’ in

sec for ‘y’ mm

height

Water discharge ‘q’

in m3/sec

Calculations:

1) D’ Aubuisson’s Efficiency = ( ) hqQqxhd

×+

Where, q = Volume of water lifted by ram in m3/sec

= Xty Cross sectional area of delivery tank

Where, y = Height of water column increase in delivery tank in m. T = Time for collecting ‘y’ m of water column. Q = Volume of water collecting in waste water tank.

XTxQ = Cross sectional area of waste water tank.

Where, x = Height of water column increase in waste water tank in m. T = Time for collecting ‘x’ m of water column

2) Rankine’s Efficiency = ( )

HQHhq d

×

−

Graph:

No of strokes per minute of waste valve Vs Rankine's Efficiency No of strokes per minute of waste valve Vs D’aubuisson’s Efficiency

sir c.r.reddy college of engineering eluru-534007 · 2. while performing the experiment on the...

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